Results of monte carlo calculations of neutron spectra and doses outside the BDMS shielding

Radev, R P ; Hall, J M

Lawrence Livermore National Laboratory

关键词: Monitoring;    Energy Range;    Neutron Spectra;    Neutrons;    Shielding;   

DOI  :  10.2172/15002961
RP-ID  :  UCRL-ID-141230
RP-ID  :  W-7405-ENG-48
RP-ID  :  15002961

美国|英语

来源: UNT Digital Library

【 摘 要 】

A set of Monte Carlo calculations of the neutron dose rates and neutron spectra outside Blend Down Monitoring System (BDMS) shielding were performed with U.S. and Russian neutron fluence-to-dose conversion coefficients. The purpose of these calculations was to facilitate the proper interpretation of the dose rate measurements from rem meters outside the BDMS shielding. An accurate determination of the dose rate is of particular interest so that dose rate can be compared with the applicable regulatory limit. The calculations show that the neutrons outside the BDMS shielding are significantly reduced in energy, i.e. the spectrum is shifted (moderated) towards the lower energies and contains significantly larger amount of neutrons in the energy range below 100 keV. The result of these calculations indicates that the dose measurement for the BDMS neutrons is overestimated from 25% to 55% depending on the location around BDMS when using either Russian or U.S. dose conversion coefficients. For an accurate neutron dose determination the application of an appropriate correcting factor to the neutron dose measurement is necessary.